For over thirty years, ion engines have been proposed for propulsion of vehicles in space. Outside of space propulsion, ion generation may also be applied to various types of materials processing systems involving ion sources, such as for ion beam etching or micromachining. Ion engines use movement of ions to provide thrust.
Generally, an ion engine has an ion accelerator system that uses an anode, a cathode, a screen grid and an accelerator grid coupled within a thruster housing. Generally, an ion engine works by generating an inert gas plasma within the thruster housing. Xenon is an example of a suitable gas. A charge within the plasma between the anode and cathode forms ions. The inert gas ions leave the thruster through the charged screen and accelerator. The net force from the ions leaving the thruster housing generates a thrust. A neutralizer is located outside the thruster housing and generates electrons. The electrons are attracted to the ions so the ions do not re-enter the thruster housing as they otherwise would in space.
A number of power supplies are used to power the various components of the system. Heaters, the accelerator, the screen, the anode and cathode of the thruster, and the anode and cathode of the neutralizer each have separate power supplies. The power supply for the screen processes a majority of the power of the spacecraft. The anode and cathode of the thruster also a substantial amount of power. The remaining four power supplies use a relatively little amount of power (less than 100 Watts).
Although the four power supplies use little power they account for a significant amount of parts and complexity. In spacecraft design, it is desirable to eliminate parts and complexity when possible. More parts increases weight of the spacecraft. More parts and complexity inherently reduces reliability.
It is therefore an object of the invention to provide a power supply system that operates reliably while maintaining good efficiency over the dynamic range.